Photosensitive Matrix Resetting for Radiological Image Quality
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Solution Overview
Problem
The existing methods for driving photosensitive devices with matrices of pixels suffer from image quality degradation due to parasitic elements causing voltage variations on column conductors during the reset phase, leading to offset shifts and loss of dynamic range in radiological image detection.
Innovation Solution
The method involves distributing rows of the matrix into groups and resetting each group sequentially, allowing simultaneous resetting of all rows within a group while resetting each group in succession to minimize charge induction on column conductors and maintain symmetry between reset and read phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single electrical pulse is applied simultaneously to all rows during the reset phase, then the resetting operation is simple and fast, but voltage variations occur on column conductors causing offset shifts and loss of dynamic range
Solution Approach 1:
The rows of the matrix are divided into multiple groups, and the reset phase is segmented into multiple sequential sub-phases. Each sub-phase resets one group of rows simultaneously while other groups remain inactive. This segmentation reduces the number of active rows during each reset sub-phase, thereby reducing charge induction on column conductors and minimizing voltage variations that cause offset shifts.
2Object-affected harmful factors
If the rising edge of the reset pulse is extended to allow charge discharge, then voltage variations are reduced, but the switching element opening time is delayed affecting image acquisition
Solution Approach 1:
By segmenting rows into groups and resetting them sequentially, the total reset time is extended without extending the reset pulse width for any individual group. Each group experiences a normal-speed reset pulse, maintaining fast switching element opening, while the sequential grouping prevents simultaneous charge induction across all rows, reducing voltage variations on column conductors.
3Manufacturing precision
If row resetting is performed sequentially one row at a time, then voltage variations on column conductors are minimized, but the total resetting time increases significantly
Solution Approach 1:
Rows are divided into multiple groups that are reset simultaneously within each group, rather than resetting rows individually. This group-based segmentation achieves a balance: fewer rows are active at any given moment compared to resetting all rows simultaneously, reducing voltage variations, while multiple rows within each group are reset in parallel, keeping the total reset time acceptable.
Solution Approach 2:
The reset phase is organized as a periodic sequence of sub-phases, where each sub-phase resets one group of rows. This periodic structure allows for systematic charge discharge between groups while maintaining a rhythmic and efficient reset process that balances precision and speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces voltage variations on column conductors, stabilizes offset images, and improves the dynamic range of useful images by optimizing the resetting process, thereby enhancing image quality.
Implementation Method 1
The photosensitive element usually consists of a diode connected in series with the switch element... The photosensitive pixel is mounted between a row conductor and a column conductor of the matrix... During the image acquisition phase, the photosensitive pixels are exposed to a signal to be picked up
Implementation Method 2
interpose, between the X-radiation and the matrix, a scintillator screen that converts the X-radiation into light radiation within the band of wavelength at which the photosensitive pixels are sensitive
Data Source
AI summary
The present invention relates to a method of driving a photosensitive device comprising a matrix of photosensitive pixels distributed at the intersections of rows and columns of the matrix. The invention relates more particularly to the control of such devices used for the detection of radiological images. The method consists in subjecting the matrix to an image cycle that includes a reset phase prior to an image acquisition phase. The rows of the matrix are distributed in several groups, and during the reset phase, the method consists in resetting all the rows in any one group simultaneously and in resetting each group of rows in succession.